1. Field of the Invention
The present invention relates to an in-mold decoration molding method and an in-mold decoration molding machine in which a pattern is printed on a film and the pattern on the film is transferred during injection molding.
2. Description of the Related Art
As a decoration molding method in the related art, there has been a method in which a pattern is printed on a film and the pattern is transferred at the same time of molding, during injection molding (for example, see Japanese Patent Unexamined Publication No. 2008-94038). FIG. 11 is a view depicting a decoration molding method in the related art, which is disclosed in Japanese Patent Unexamined Publication No. 2008-94038. A molding die for injection molding of a resin material is configured to include first die 1 and a second die (not illustrated), film 3 is interposed between first die 1 and the second die (not illustrated), and a resin is injected on film 3 sealed in the dies. In this manner, a decoration film or functional film printed or stacked on film 3 is transferred onto a molded body while an injection-molded body is molded with high accuracy. Film 3 is supplied in a roll shape.
In general, the decoration molding method is performed in the following procedure. First, a decoration film or a functional film is printed or transferred and stacked on film 3 having the roll shape, in advance, and film 3 is disposed between first die 1 and a second die (not illustrated) of the molding die. Next, film 3 is fixed to first die 1 using clamp jig 4. Then, the second die (not illustrated) is caused to move and comes into close contact with first die 1, and a predetermined amount of a molten resin is injected between first die 1 and the second die (not illustrated), and a predetermined molded body is molded. At this time, the decoration film on film 3 is transferred to a molded product. After a certain period of time of cooling, the molded product is taken out.
In the decoration molding method, particularly, film 3 needs to extend along a surface of a die part of first die 1, at this time, film 3 is fixed to the surface of the die part of first die 1 through adsorption, the adsorption is released when the molded product is taken out, and, in general, the molded product is taken out.
In general, in the decoration molding method, a film, to which a decoration film adheres, is caused to be shaped after a die shape by injecting a resin, and thus, in a case where a molded product has a deep drawing shape, the film in the molding die significantly extends, the film extends exceeding the elastic limit of the film itself and the decoration film, and thus, the film becomes partially thin. In this case, when the dies are closed, a thin portion of the film or the decoration film receives stress exceeding breaking limit stress and is torn in some cases. When the film is torn, a torn piece is generated in some cases. At this time, there are drawbacks in that the inside of the molding die is filled with torn pieces of the film, the torn piece is stuck to a die molding surface, and the molded product has an external defect such as a dent or damage.
In Japanese Patent Unexamined Publication No. 2008-94038, in order to solve the above drawbacks, film heating heater 22, which heats film 3 on the molding die, is disposed between first die 1 and film supply device 19 which includes a supply mechanism of the film and a winding mechanism of the film. Before film 3 is caused to be shaped after the molding die shape, film 3 extends by being heated to a temperature near the softening point. Therefore, it is easy to supply film 3 in the molding die and to cause film 3 to be shaped after the molding die shape.